4100

4100 = 2 x 2 x 5 x 5 x 41.

4100 is 5555 in base 9. It is 12121212 in base 3 (A037480 and A162216).

4100 is a multiple of 5 with a digit sum of 5 (A069540).

4100 has three representations as a sum of two squares (A025286): 4100 = 2² + 64² = 16² + 62² = 40² + 50².

4100 divides 31¹⁰ - 1.

Source: What's Special About This Number?